Crop header with draper canvas and a seal with an element of the cutter bar

ABSTRACT

A crop harvesting header with a cutter bar and a draper assembly has a draper canvas with a plurality of transverse slats with a resilient strip across a front edge of the outer surface in front of the front end of the slats to cooperate with a rearwardly projecting element of the cutter bar extending over the upper run of the draper canvas to engage the upper surface of said strip to form a seal to inhibit entry between the cutter bar and the draper canvas of materials carried by the cut crop. There is also provided a bead on the canvas on the surface opposite the strip within the width of the strip. The arrangement can be symmetrical with a strip at each of the front and rear edges spanned by the slats extending between them, with beads on each edge opposite the front and rear strips respectively.

This invention relates to a header for cutting and transporting astanding crop with a transverse leading cutter bar and particularly toan arrangement which provides a seal between a front edge of a drapercanvas and an element of the cutter bar and to a draper canvas designedfor use with the header.

BACKGROUND OF THE INVENTION

Draper headers generally include a header frame, an elongate cutter baralong a front edge of the frame including a cutter bar beam whichcarries a plurality of knife guards for guiding reciprocating movementof a sickle knife across a front edge of the cutter bar. On the headeris also mounted a draper assembly including a first and second draperguide roller each arranged at a respective end of the draper assemblyspaced apart along the cutter bar with an axis of each roller extendingsubstantially at right angles to the cutter bar, a draper canvas forminga continuous loop of flexible material wrapped around the rollers so asto define a front edge of the canvas adjacent the cutter bar, a rearedge of the canvas spaced rearwardly of the cutter bar, an upper run ofthe canvas on top of the roller and a lower run of the canvas below therollers. The cut crop thus falls rearwardly onto the upper run of thecanvas and is transported longitudinally of the header. Generally,between the draper rollers there is provided a support plate assemblyfor the upper run of the draper canvas to prevent sagging.

The header of this type can be used simply for forming a swath in whichcase the material is carried to a discharge opening of the header anddeposited therefrom onto the ground. Headers of this type can also beused for feeding a combine harvester so that the materials are carriedto an adapter member positioned at the discharge opening of the headerfor carrying the materials from the discharge opening into the feederhousing of the combine harvester. Yet further, headers of this type canbe used for hay conditioners in which the material from the dischargeopening is carried into crushing rolls. It will be appreciated,therefore, that the use of the header is not limited to particular typesof agricultural machine but can be used with any such machine in whichit is necessary to cut a standing crop and to transport that crop whencut longitudinally of the header for operation thereon.

The draper canvas normally comprises a fabric which is coated with arubber material which is then vulcanized after forming of the fabricinto the required shape and after attachment thereto of transverseslats.

The arrangement of the above patent has achieved significant success andhas been used for many years. It provides a seal between an undersurface of a rearwardly extending element of the cutter bar and a frontedge portion of the upper surface of the canvas.

Also not shown in the above patent is the conventional guidingarrangement to prevent misalignment of the draper canvas on the rollersand this is provided by a bead located on the underside of the canvaswhich runs in a groove in the roller.

An alternative arrangement is shown in U.S. Pat. No. 6,351,931 (Shearer)issued Mar. 5, 2002 also of the present Assignees. This provides anadditional guide bead on the outer surface of the canvas which runs incontact with the edge of the element of the cutter bar. This arrangementhas not been successful and has not been adopted since it failed toprovide the expected improvements over the Talbot and Fox arrangement.

SUMMARY OF THE INVENTION

It is one object of the invention to provide a further design of headerand particularly the draper canvas therefore which can assist inproviding a seal between the canvas and the cutter bar,

According to one aspect of the invention there is provided a header forcutting and transporting a standing crop comprising:

a header frame;

an elongate cutter bar arranged along a front edge of the frame;

a knife mounted on the cutter bar for cutting the standing crop;

a draper assembly mounted on the header frame rearwardly of the cutterbar such that cut crop falls onto the draper assembly for transportationlongitudinally of the header;

the draper assembly including a first and a second draper guide rollereach arranged at a respective end of the draper assembly spaced apartalong the cutter bar with an axis of each guide roller arrangedsubstantially at right angles to the cutter bar;

the draper assembly including a draper canvas forming a continuous loopof flexible material wrapped around the rollers so as to define an upperrun of the draper canvas on top of the rollers and a lower run of thedraper canvas below the rollers and so as to define an outer surfacefacing outwardly and an opposed inner surface;

a front edge of the upper run of the draper canvas being arrangedunderneath the cutter bar, and a rear edge of the upper run of thedraper canvas being spaced rearwardly of the cutter bar;

a front draper support plate defining a substantially horizontal supportsurface lying under the upper run adjacent the front edge thereof andextending therealong between the first and second guide rollers;

the first and second guide rollers each having a front end thereofrecessed rearwardly of the front edge of the upper run of the drapercanvas and the support plate having a front edge thereof recessedrearwardly of the front edge of the upper run of the draper canvas suchthat the upper run of the draper canvas includes a portion thereof atthe front edge which is cantilevered forwardly of the rollers and of thesupport plate;

the draper canvas including a base layer of a sheet material;

the draper canvas including an additional strip of a resilient materialattached on to the base layer at or adjacent the front edge on the outersurface and extending rearwardly from the front edge of the drapercanvas to a rear edge of the strip spaced rearwardly of the front edge;

the strip standing outwardly of the outer surface from the base layer todefine an outer surface of the strip raised from the base layer;

the cutter bar including an element thereof extending rearwardly overthe upper run of the draper canvas to a position rearwardly of the frontedge of the upper run of the draper canvas and forwardly of the frontend of the rollers and of the front edge of the support plate andengaging the upper surface of said strip on the draper canvas so thatthe engagement between the element of the cutter bar and the uppersurface of the strip forms a seal to inhibit entry between the cutterbar and the draper canvas of materials carried by the cut crop.

It will be appreciated that the term “draper canvas” is a traditionalterm based upon the material from which the “canvas” was made but thatthis term no longer provides any indication of nor limitation to the useof particular materials for the base fabric from which the “canvas” ismade. Many synthetic material can thus be used. Commonly the canvas iscoated with a rubber layer and again many different resilient coatingmaterials can be used and no limitation is intended herein in thisregard.

While the knife used with the cutter bar is usually of the sickle knifetype including a plurality of knife guards mounted on the cutter bar,other types of knife can also be used.

In some embodiments, the cutter bar itself comprises a channel shapedmember which defines the trailing edge as an integral portion of thecutter bar itself. In other embodiments, the cutter bar forms in effecta single bar carrying the sickle knife with a separate canvas carrierelement in the form of a plate attached to and carried by the cutterbar. In this latter arrangement, the trailing edge can be provided bythe edge of the canvas carrier rather than the cutter bar itself.However it will be appreciated that in both arrangements the guide beadengages an edge which is fixed relative to the cutter bar and thus isguided in position relative to the cutter bar as it moves along thecutter bar.

Preferably the strip of resilient material at the front edge is ofsubstantially constant thickness such that the upper surface issubstantially flat so as to define a flat surface in contact with acorresponding flat surface of the element of the cutter bar. Howeverother shapes may be provided including narrower raised portions.

Preferably the front edge of the strip of resilient material at thefront edge is located at the front edge of the canvas. However it mayberecessed slightly rearwardly to leave a bare edge portion withoutinterfering with the operation.

Preferably the rear edge of the strip of resilient material at the frontedge is substantially coincident with the rear edge of the element. Thisis the intention in order that the sealing surface be coincident.However it will be appreciated that the rear edge of the strip can beslightly retarded from or slightly proud of the rear edge of the elementwithout interfering with the operation.

Preferably the rear edge of the strip is in front of the front edge ofthe support plate. In this way the strip is cantilevered forwardly ofthe support plate and thus part of the canvas which is free to flex frompressure from the element of the cutter bar.

Preferably the strip of resilient material at the front edge is shapedsuch that the strip has a width from the front edge to its rear edgewhich is greater than its height from the outer surface of the canvas.This provides a seal of sufficient width to be effective withoutinterfering with the flexibility of the canvas to traverse around theroller. Typically the strip has a width of the order of 25 mm and aheight of the order of 4 mm.

As conventionally, the draper canvas is preferably formed of a layer offabric material with a resilient coating on the layer of the fabricmaterial.

Preferably the draper canvas has a folded edge at least at the frontedge and more preferably the folded edge is folded back on the outersurface of the fabric material for enhanced stiffness.

Preferably the draper canvas includes a second strip on the rear edgelocated and arranged symmetrically relative to the strip on the frontedge for reversibility of the canvas when worn.

In this arrangement, the draper canvas preferably has a bead of aresilient material attached on the inner surface adjacent the front edgeand a second bead of a resilient material adjacent the rear edge locatedand arranged symmetrically relative to the bead adjacent the front edge.

Preferably each of the beads is arranged so as to lie on the innersurface opposite to the respective strip within the width of therespective strip. The front bead therefore has no effect since it islocated underneath the strip forwardly of the roller and support platebut the rear bead is a guide bead for cooperating with a groove in theroller. The symmetrical arrangement again allows reversibility.

Preferably the draper canvas has a plurality of slats arrangedtransverse to a direction of movement of the draper canvas with theslats having a height from the draper canvas which is greater than theheight of the strip from the draper canvas. Preferably each of the slatshas a front end spaced rearwardly from the rear edge of the strip.

Preferably the strip and the slats are molded integrally so that thereis provided a plurality of pieces of resilient material each connectinga forward end of a respective one of the slats to the strip with thepieces having a height from the draper canvas which is substantiallyequal to the height of the strip from the draper canvas.

Preferably to provide the above symmetrical arrangement, the drapercanvas includes a second strip on the rear edge located and arrangedsymmetrically relative to the strip on the front edge with the secondstrip having a front edge at or adjacent the rear edge of the drapercanvas and a rear edge spaced from the rear edge of the draper canvasand the draper canvas has a bead of a resilient material attached on theinner surface adjacent the front edge of the draper canvas and a secondbead of a resilient material adjacent the rear edge of the draper canvaslocated and arranged symmetrically relative to the bead adjacent thefront edge of the draper canvas, with the slats extending between thestrip and the second strip.

According to a second aspect of the invention there is provided a drapercanvas for use with a draper assembly of a header for cutting andtransporting a standing crop where the draper assembly includes a firstand a second draper guide roller and where the draper canvas is arrangedfor forming a continuous loop of flexible material wrapped around therollers so as to define an upper run of the draper canvas on top of therollers and a lower run of the draper canvas below the rollers and so asto define an outer surface facing outwardly and an opposed innersurface;

the draper canvas comprising:

a base layer of a sheet material;

an additional strip of a resilient material attached on to the baselayer at or adjacent the front edge on the outer surface and extendingrearwardly from the front edge of the draper canvas to a rear edge ofthe strip spaced rearwardly of the front edge;

the strip standing outwardly of the outer surface from the base layer todefine an outer surface of the strip raised from the base layer;

the strip being shaped such that the strip has a width from the frontedge to its rear edge which is greater than its height from the outersurface of the canvas;

and a plurality of slats arranged transverse to a direction of movementof the draper canvas with the slats having a height from the base layerwhich is greater than the height of the strip from the base layer, eachof the slats having a front end rearward from the rear edge of thestrip.

BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment of the invention will now be described in conjunctionwith the accompanying drawings in which:

FIG. 1 is a top plan view of the front part of a header according to thepresent invention.

FIG. 2 is a cross sectional view along the lines 2-2 of FIG. 1 showingthe front part of the header and draper canvas.

FIG. 3 is a cross sectional view along the lines 2-2 of FIG. 1 showingthe rear part of the header and draper canvas and the co-operation ofthe rear guide bead with a groove in the roller.

FIG. 4 is a cross sectional view through one edge of the canvas onlytaken at location where there is no transverse slat.

FIG. 5 is a cross sectional view through one edge of the canvas onlytaken at a transverse slat.

In the drawings like characters of reference indicate correspondingparts in the different figures.

DETAILED DESCRIPTION

Only those parts of the header which are of importance to the presentinvention are shown in the above figures of the present application andthe remaining parts of the header including the frame structure, drives,ground wheels and the like are omitted as these will be well known toone skilled in the art. The present invention is concerned with the areaof co-operation between the front and rear edges of the draper with thecutter bar and with the rear header plate respectively and thereforethese elements only are shown in detail.

Many of the figures and much of the following description is taken fromthe aforementioned U.S. Pat. Nos. 5,458,586 and 6,351,931 of the presentassignees since these show the basic construction of the header andthose drawings have been modified to include the details of the presentinvention as described hereinafter.

The header therefore comprises a frame, one element of which isindicated at 10 in the form of a beam extending horizontally andforwardly from a rear support frame structure (not shown) to a cutterbar assembly generally indicated at 11 for support of that cutter barassembly. The beam 10 forms one of a plurality of such beams arranged atspaced positions along the length of the header frame so as to supportthe cutter bar assembly 11 as an elongate structure across the frontedge of the header.

The cutter bar comprises a generally C-shaped beam 12 which providesstructural support for the cutter bar with the C-shaped beam beingwelded to the front ends of the forwardly extending beams 10. TheC-shape beam 12 includes a top plate portion 13, a bottom plate portion14 and a forward plate portion 15 which converges from the top andbottom plate portions toward a front apex 16 forming a forward mostpoint of the beam 12. At the apex 16 is welded a longitudinallyextending bar 17 which forms a support for a plurality of knife guards18 only some of which are shown in FIG. 1 for convenience ofillustration. The knife guards are of course of well known constructionand their shape is shown only schematically. The knife guards carry asickle knife assembly 20 having a longitudinally reciprocating bar 21driving a plurality of triangular knife blades 22 which sit on the knifeguards and reciprocate back and forth across the knife guards in acutting action. Again this construction is well known and thereforedetail is not necessary.

The cutter bar support beam 12 also carries an elongate angle iron 23which is welded onto the top plate portion 13 on the underside thereofat the front edge thereof with the angle iron extending verticallydownwardly and then forming a support plate 24 extending forwardlytherefrom toward the apex 16.

The draper assembly generally indicated at DA includes a first drapersupport roller 30 and a second draper support roller (not shown). One ofthese rollers is driven by a drive motor (not shown) to effect rotationof the draper in conventional manner. The draper assembly furtherincludes a draper canvas 32 in the form of a continuous loop or band offabric which is wrapped around the rollers at respective ends to form anupper run 33 of the draper canvas on top of the rollers and a lower run34 of the canvas underneath the rollers. The rollers are thus spacedlongitudinally of the cutter bar and arranged with their axes ofrotation parallel and at right angles to the cutter bar. The drapercanvas thus includes a front edge 35 of the upper run which is adjacentthe cutter bar and a rear edge 36 of the upper run 33 which is remotefrom the cutter bar and spaced rearwardly therefrom thus definingtherebetween a flat surface of the upper run for transportation of thecrop longitudinally of the header. The lower run 34 also includes afront edge 37 and a rear edge. The draper canvas includes a plurality ofconventional transverse slats 39 which assist in carrying the crop alongthe draper canvas. Each edge of the draper canvas can include aconventional folded seam so as to define a portion of the canvasmaterial which is folded back as indicated at 40 with that folded backportion being folded back on top of the fabric layer and bonded to thecanvas by the vulcanization effect in the manufacture of the canvas.

The upper run of the draper canvas is supported by a support plateassembly 45 which includes a front plate and includes a center plate andrear plates which are not shown for convenience of illustration. Thefront plate includes a horizontal top plate portion 46, shown in phantomin FIG. 1, lying underneath the upper run of the draper canvas adjacentthe front edge for supporting that front edge in sliding movement acrossthe top surface of that plate. The support plate 46 further includes avertical plate portion, which extends downwardly from a front edge ofthe top plate portion (not shown in the figures). At a bottom edge ofthe vertical plate portion is provided a lower horizontal plate portionthus forming the front support plate into a generally C-shape to providestructural strength so that the support plate is essentially selfsupporting mounted on mounting brackets (also not shown).

The rollers 30 are carried on the support plate 46. Further details ofthe brackets and support elements are described in the above patent ofTalbot.

The length of the bracket 25 is arranged so that the front edge 49 ofthe support plate is spaced rearwardly from the front edge 35 of theupper run of the draper canvas. In addition the front end of the rollers30 is spaced rearwardly from the front edge 35 of the upper run of thecanvas. This recessing of the front edges of the support plate memberand of the rollers provides a portion 70 of the front edge of the drapercanvas which is cantilevered outwardly beyond the support provided bythose elements.

The beam 12 of the cutter bar is shaped so that the top plate portion 13extends rearwardly to a rear edge 71 which overlaps the portion 70. Therear edge 71 is located therefore at a position rearwardly of the frontedge 35 of the draper canvas and in a position forwardly of the frontedge 49 of the support plate and the front ends 65 of the draperrollers. That portion of the draper canvas therefore which engages theunderside 72 of the top plate portion 13 is unsupported on its undersideand is therefore free to flex downwardly should it be depresseddownwardly by the presence of material collecting on the under surface72. The top plate portion 13 of the beam 12 is substantially horizontalthat is parallel to the generally horizontal surface of the upper run.The cooperation therefore between the surface 72 of the upper plateportion 13 and the upper surface of the draper canvas at the portion 70provides a seal which inhibits the tendency of materials to pass betweenthe draper canvas and the cutter bar. This seal therefore inhibits thebuild-up of materials inside the C-shape of the cutter bar and betweenthe draper canvas upper run and lower run and around the draper rollerswhich can of course cause damage.

At the rear edge 36, the draper canvas is guided on the draper roller bya V groove 30A in the roller 30 into which projects from the back of thecanvas a V-shaped guide rib 75 which runs along the inner surface of thecanvas along its full length.

The construction of the draper of the present invention as shown inFIGS. 4 and 5. Thus the draper of the present invention is symmetricalin that the draper can be reversed by rotating the draper so that thefront edge is turned to become the rear edge and vice versa. Thus onlythe front edge is shown in FIGS. 1, 4 and 5 with it being understoodthat the rear edge is exactly symmetrical. Thus in FIG. 4 is shown aportion of the draper canvas which includes a base layer or sheet 80which is formed of a fabric sheet 81 which is folded at its edge 82 toform a portion 83 which is folded back on top of the layer 81 to form anend edge 84 of the folded back portion 83 which lies on top of thefabric of the layer 81 spaced away from the edge 82. The canvas carriesa coating or infused rubberized layer in a conventional manner. At theedge 82 is provided a strip 86 of a resilient material. The resilientmaterial is preferably of the same construction as the rubberizedcoating so that it can be vulcanized with the structure of the canvasand molded in place as part of the manufacturing process. The strip 86has a front edge 87 which is at or immediately adjacent the edge 82 ofthe base layer of the canvas. In the embodiment shown the front edge 87of the strip is immediately coincident with the edge 82. The stripincludes a rear edge 88 spaced away from the edge 87 into the body ofthe canvas. The strip has an upper surface 89 which is flat and smooth.Thus the strip is rectangular with the side edges 87 and 88 beingvertical and the top surface 89 horizontal. However the strip may beshaped with inclined or tapered side edges 87 and 88.

In the example shown the strip has the width of the order of 1″ (25 mm)and a height of the order of ⅙″ (4.0 mm). The strip thus stands up fromthe upper surface of the base layer of the draper canvas that is theupper surface of the folded back portion 83.

On the underside of the draper canvas is molded the bead 75 which isgenerally V shaped so that the sides are tapered downwardly and inwardlyto a bottom surface 75A which is narrower than the base of the bead. Thebead is located at a position spaced from the edge 82 but underlying thestrip 86 so that the edge of the bead is spaced from the edge 82 by adistance less than the edge 88 of the strip.

As shown in FIG. 5 the canvas also carries slats 39 which stand upwardlyfrom the upper surface of the canvas to a top edge 39A which is at aheight significantly greater than the height of the strip 86. Each slatextends transversely across the draper canvas to a position closelyadjacent the strip at the respective side edges of the canvas. Thus eachslat extends to an end edge 39B which is spaced from the side edge 82 bya distance greater than the spacing of the edge 88 of the strip so thatthe edge 39B of the slat is spaced from the edge 88 of the strip. Theslats 39 are molded integrally with the strip 86 by providing portions90 which extend from the edge 39B of the slat to the edge 88 of thestrip 86. These portions as best shown in FIG. 1 have a width equal tothe width of the slat 39 to which they are attached and a height (asshown in FIG. 5) equal to the height of the strip 86. These portionsthus act to integrate the structure so that the slats connect into thestrip to reduce the tendency of the slats to tear away from the canvassince the same resilient material forming the strip extends into theslat and thus is resistant to stripping or tearing from the base layerof the draper canvas. In the example shown, the bead 75 has a width atits base of the order of ½″ (13 mm) and a height from the under-surfaceof the canvas of the order ⅓″ (8 mm). The center of the bead is spacedfrom the edge 82 by a distance of the order of ⅔″ (16 mm). This suitablylocates the bead at a position on the canvas for cooperation with thegroove in the roller at the rear of the canvas as best shown in FIG. 3.

Turning now to FIG. 2, it will be noted that the side edge 88 of thestrip is substantially coincident with the end edge 71 of the plate 13so that the whole of the strip 86 underlies the plate 13. The presenceof the strip 86 provides an improved sealing effect between the surface89 of the strip and the surface 72 of the plate 13 due to an increase inpressure therebetween. In addition the presence of the shoulder or edge88 provides a raised surface standing upwardly from surface of thecanvas to inhibit the penetration of material into the space between thesurfaces 89 and 72. The surface 89 is formed as a flat surface moldedonto the top of the resilient strip so that the surface 89 can be formedif required. Also it is or can be smoother than the surface of thecanvas itself to provide an improved contact surface engaging thesurface 72.

It will be noted in FIG. 2 that the bead 75 at the front edge is locatedat a position spaced forwardly of the edge 49 of the support plate andforwardly of the end of the roller. Thus the bead 75 at the front edgeof the canvas has no effect since it is engaging no component of theroller or support plate. However it will be noted that the bead 75 atthe rear edge is located in engagement with a groove in the roller. Inthis way wear of the structure takes place at the strip 86 at the frontedge and the bead 75 at the rear edge. These two components are worn inuse so that the strip 86 at the rear edge and the bead 75 at the frontedge remain unworn. Rotation of the canvas when the wear has becomeexcessive allows therefore the canvas to continue in use while the strip86 from the rear edge is moved for the sealing effect at the front edgeand the bead 75 is moved to the rear edge for providing guiding action.

The arrangement disclosed herein therefore provides an effective guidingaction which is improved relative to the above patent of Shearer. Thesealing action provided by the additional resilient strip 86significantly enhances the sealing effect relative to the abovearrangement of Talbot.

Since various modifications can be made in my invention as herein abovedescribed, and many apparently widely different embodiments of same madewithin the spirit and scope of the claims without department from suchspirit and scope, it is intended that all matter contained in theaccompanying specification shall be interpreted as illustrative only andnot in a limiting sense.

1. A header for cutting and transporting a standing crop comprising: aheader frame; an elongate cutter bar arranged along a front edge of theframe; a knife mounted on the cutter bar for cutting the standing crop;a draper assembly mounted on the header frame rearwardly of the cutterbar such that out crop falls onto the draper assembly for transportationlongitudinally of the header; the draper assembly including a first anda second draper guide roller each arranged at a respective end of thedraper assembly spaced apart along the cutter bar with an axis of eachguide roller arranged substantially at right angles to the cutter bar;the draper assembly including a draper canvas forming a continuous loopof flexible material wrapped around the rollers so as to define an upperrun of the draper canvas on top of the rollers and a lower run of thedraper canvas below the rollers and so as to define an outer surfacefacing outwardly and an opposed inner surface; a front edge of the upperrun of the draper canvas being arranged underneath the cutter bar, and arear edge of the upper run of the draper canvas being spaced rearwardlyof the cutter bar; a front draper support plate defining a substantiallyhorizontal support surface lying under the upper run adjacent the frontedge thereof and extending therealong between the first and second guiderollers; the first and second guide rollers each having a front endthereof recessed rearwardly of the front edge of the upper run of thedraper canvas and the support plate having a front edge thereof recessedrearwardly of the front edge of the upper run of the draper canvas suchthat the upper run of the draper canvas includes a portion thereof atthe front edge which is cantilevered forwardly of the rollers and of thesupport plate; the draper canvas including a base layer of a sheetmaterial; the draper canvas including an additional strip of a resilientmaterial attached on to the base layer at or adjacent the front edge onthe outer surface and extending rearwardly from the front edge of thedraper canvas to a rear edge of the strip spaced rearwardly of the frontedge; the strip standing outwardly of the outer surface from the baselayer to define an outer surface of the strip raised from the baselayer; the cutter bar including an element thereof extending rearwardlyover the upper run of the draper canvas to a position rearwardly of thefront edge of the upper run of the draper canvas and forwardly of thefront end of the rollers and of the front edge of the support plate andengaging the upper surface of said strip on the draper canvas so thatthe engagement between the element of the cutter bar and the uppersurface of the strip forms a seal to inhibit entry between the cutterbar and the draper canvas of materials carried by the cut crop.
 2. Theheader according to claim 1 wherein the strip is of substantiallyconstant thickness such that the upper surface is substantially flat. 3.The header according to claim 1 wherein the front edge of the strip islocated at the front edge of the canvas.
 4. The header according toclaim 1 wherein the rear edge of the strip is substantially coincidentwith the rear edge of the element.
 5. The header according to claim 1wherein the rear edge of the strip is in front of the front edge of thesupport plate.
 6. The header according to claim 1 wherein the strip isshaped such that the strip has a width from the front edge to its rearedge which is greater than its height from the outer surface of thecanvas.
 7. The header according to claim 6 wherein the strip has a widthof the order of 25 mm and a height of the order of 4 mm.
 8. The headeraccording to claim 6 wherein draper canvas is formed of a layer offabric material with a resilient coating on the layer of the fabricmaterial.
 9. The header according to claim 8 wherein the draper canvashas a folded edge at the front and rear edge.
 10. The header accordingto claim 9 wherein the folded edge is folded back on the outer surfaceof the fabric material.
 11. The header according to claim 1 wherein thedraper canvas includes a second strip on the rear edge located andarranged symmetrically relative to the strip on the front edge.
 12. Theheader according to claim 11 wherein the draper canvas has a bead of aresilient material attached on the inner surface adjacent the front edgeand a second bead of a resilient material adjacent the rear edge locatedand arranged symmetrically relative to the bead adjacent the front edge.13. The header according to claim 12 wherein each of the beads isarranged so as to lie on the inner surface opposite to the respectivestrip within the width of the respective strip.
 14. The header accordingto claim 1 wherein the draper canvas has a plurality of slats arrangedtransverse to a direction of movement of the draper canvas with theslats having a height from the draper canvas which is greater than theheight of the strip from the draper canvas, each of the slats having afront end spaced rearwardly from the rear edge of the strip.
 15. Theheader according to claim 14 wherein there is provided a plurality ofpieces of resilient material each connecting a forward end of arespective one of the slats to the strip with the pieces having a heightfrom the draper canvas which is substantially equal to the height of thestrip from the draper canvas.
 16. The header according to claim 14wherein the draper canvas includes a second strip on the rear edgelocated and arranged symmetrically relative to the strip on the frontedge with the second strip having a front edge at or adjacent the rearedge of the draper canvas and a rear edge spaced from the rear edge ofthe draper canvas and wherein the draper canvas has a bead of aresilient material attached on the inner surface adjacent the front edgeof the draper canvas and a second bead of a resilient material adjacentthe rear edge of the draper canvas located and arranged symmetricallyrelative to the bead adjacent the front edge of the draper canvas, withthe slats extending between the strip and the second strip.
 17. A drapercanvas for use with a draper assembly of a header for cutting andtransporting a standing crop where the draper assembly includes a firstand a second draper guide roller and where the draper canvas is arrangedfor forming a continuous loop of flexible material wrapped around therollers so as to define an upper run of the draper canvas on top of therollers and a lower run of the draper canvas below the rollers and so asto define an outer surface facing outwardly and an opposed innersurface; the draper canvas comprising: a base layer of a sheet material;an additional strip of a resilient material attached on to the baselayer at or adjacent the front edge on the outer surface and extendingrearwardly from the front edge of the draper canvas to a rear edge ofthe strip spaced rearwardly of the front edge; the strip standingoutwardly of the outer surface from the base layer to define an outersurface of the strip raised from the base layer; the strip being shapedsuch that the strip has a width from the front edge to its rear edgewhich is greater than its height from the outer surface of the canvas;and a plurality of slats arranged transverse to a direction of movementof the draper canvas with the slats having a height from the base layerwhich is greater than the height of the strip from the base layer, eachof the slats having a front end rearward from the rear edge of thestrip.
 18. The draper canvas according to claim 17 wherein the strip isof substantially constant thickness such that the upper surface issubstantially flat.
 19. The draper canvas according to claim 17 whereinthe front edge of the strip is located at the front edge of the canvas.20. The draper canvas according to claim 17 wherein the strip has awidth of the order of 25 mm and a height of the order of 4 mm.
 21. Thedraper canvas according to claim 17 having a folded edge at the frontand rear edge.
 22. The draper canvas according to claim 21 wherein thefolded edge is folded back on the outer surface of the base layer. 23.The header according to claim 17 including a second strip on the rearedge located and arranged symmetrically relative to the strip on thefront edge with the second strip having a front edge at or adjacent therear edge of the draper canvas and a rear edge spaced from the rear edgeof the draper canvas and wherein the draper canvas has a bead of aresilient material attached on the inner surface adjacent the front edgeof the draper canvas and a second bead of a resilient material adjacentthe rear edge of the draper canvas located and arranged symmetricallyrelative to the bead adjacent the front edge of the draper canvas. 24.The draper canvas according to claim 23 wherein each of the beads isarranged so as to lie on the inner surface opposite to the respectivestrip within the width of the respective strip.
 25. The draper canvasaccording to claim 17 wherein there is provided a plurality of pieces ofresilient material each connecting a forward end of a respective one ofthe slats to the strip with the pieces having a height from the drapercanvas which is substantially equal to the height of the strip from thedraper canvas.